A tire comprises several rubber profiled elements superposed on one another and reinforcing threads embedded in the rubber of some of these profiled elements. The term “thread” is to be interpreted here in a general sense. Thus, in what follows, a monofilament thread, a multifilament thread, a cord or a folded yarn for example will be termed a thread. The thread may or may not be surface treated. These threads form plies and are laid substantially parallel to one another within one and the same ply. The threads reinforce the tire to improve its strength and robustness. Some of these threads are made of a magnetic material, for example of steel, notably in tires for vehicles of the heavy vehicle type. The embedded threads form plies.
In order to monitor or check the condition of a tire, notably when the tire is worn, it is recommended that each reinforcing thread be checked in order to make sure than none of them has a defect that could compromise the integrity of the tire. The term “defect” is to be interpreted here as referring to an irregularity in the thread. This irregularity could notably be a cut, a destranding, or alternatively a significant reduction in the cross section of the thread as a result of the wearing, corroding or oxidation of the thread.
The prior art discloses a checking facility that uses X-ray inspection. However, such a facility is relatively expensive and requires a high level of investment.
Also, document U.S. Pat. No. 6,005,388 discloses a device for checking the tire. The device comprises a receiver member that receives a magnetic flux generated from two induction members. The magnetic flux generates, within the receiver member, a condition signal representative of the threads facing the receiver member. However, such a device is capable of roughly identifying a region containing a number of threads which may possibly include defective threads, without being capable of identifying precisely which threads are the defective ones.